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Structural control on megathrust rupture and slip behavior: Insights from the 2016 Mw 7.8 Pedernales Ecuador earthquake

February 17, 2020

The heterogeneous seafloor topography of the Nazca Plate as it enters the Ecuador subduction zone provides an opportunity to document the influence of seafloor roughness on slip behavior and megathrust rupture. The 2016 Mw 7.8 Pedernales Ecuador earthquake was followed by a rich and active postseismic sequence. An internationally coordinated rapid response effort installed a temporary seismic network to densify coastal stations of the permanent Ecuadorian national seismic network. A combination of 82 onshore short and intermediate period and broadband seismic stations and six ocean bottom seismometers recorded the postseismic Pedernales sequence for over a year after the mainshock. A robust earthquake catalog combined with calibrated relocations for a subset of magnitude ≥4 earthquakes shows pronounced spatial and temporal clustering. A range of slip behavior accommodates postseismic deformation including earthquakes, slow slip events, and earthquake swarms. Models of plate coupling and the consistency of earthquake clustering and slip behavior through multiple seismic cycles reveal a segmented subduction zone primarily controlled by subducted seafloor topography, accreted terranes, and inherited structure. The 2016 Pedernales mainshock triggered moderate to strong earthquakes (5 ≤ M ≤ 7) and earthquake swarms north of the mainshock rupture close to the epicenter of the 1906 Mw 8.8 earthquake and in the segment of the subduction zone that ruptured in 1958 in a Mw 7.7 earthquake.

Publication Year 2020
Title Structural control on megathrust rupture and slip behavior: Insights from the 2016 Mw 7.8 Pedernales Ecuador earthquake
DOI 10.1029/2019JB018001
Authors Lillian Soto-Cordero, Anne Meltzer, Eric A. Bergman, Mariah Hoskins, Joshua C. Stachnik, Hans Agurto-Detzel, Alexandra Alvarado, Susan L. Beck, Philippe Charvis, Yvonne Font, Gavin P. Hayes, Stephen Hernandez, Sergio Leon-Rios, Colton Lynner, Jean-Mathieu Nocquet, Marc Regnier, Andreas Rietbrock, Frederique Rolandone, Mario Ruiz
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research: Earth Surface
Index ID 70209858
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center